Single use, topical, hydrophilic article with a hemostatic foam

ABSTRACT

A hemostatic surface application device having a region of hemostatic foam for contact with a patient&#39;s skin where a wound exists or is created, the device includes: a release layer, the release layer in contact with a hemostatic flexible foam section, and a structural foam layer having a front side and a back side surrounding the hemostatic flexible foam layer, forming a generally central hemostatic surface exposed through the front side of the surrounding structural foam layer, and a support layer adhered to the backside of the structural foam layer.

RELATED APPLICATION DATA

This application claims priority under 35 U.S.C. 120 as aContinuation-in-Part Application of copending U.S. patent applicationSer. No. 17/168,128, filed 4 Feb. 2021 and titled SINGLE USE, TOPICAL,HYDROPHILIC ARTICLE WITH A HEMOSTATIC FOAM.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the field of topical, substantivelynon-transferring application of a medicinal or therapeutic device totissue particularly for the reduction of bleeding, especially forenhancing the formation of clots on the surface of patients as wounddressing applied over vascular puncture sites and percutaneous cathetersites.

2. Background of the Art

External wounds and concomitant bleeding are the most common injuriessuffered by animals. Scratches, cuts, abrasions, lacerations, puncturesand other categories of damage to layers of tissue, especially skin,each act to breach the protective tissue and blood vessels, allowingblood to flow out of its normal passageways. Bleeding provides a firstline defense against damage from the ancillary effects of the traumathat caused the injury. The flow of blood washes material out of thewound and the blood clots to seal the wound area. The types of materialswashed from the wound by the flow of blood from the traumatized areaincludes material introduced into the wound area by any foreign objectwhich caused the wound (including biological species such as bacteriaand viruses and inorganic species such as particulates). The clottingprevents migration of materials into the wound area, and therefore intothe animals' body, thus reducing the likelihood of subsequent infectionof the wound, even after materials originally introduced into the woundhave been removed or reduced in volume by the initial blood flow.

Clotting is essential to both the short term and long term process ofhealing the wound. In the short term, after the wound has been partiallycleansed by blood flow, the clotting entraps these removed materials sothat they will not easily reenter the wound and stops the blood flow sothat excessive blood loss will not occur. In the long term, the clotsecures the wound minimizing additional tissue trauma (e.g., fromflexing of the area) and preventing additional contaminants fromentering the wound and blood stream.

Clotting is a complex biological process, driven by a series ofcascading organic/biological chemical reactions which must occur in aspecific sequence to cause the final effect of protecting the wound. Inlay terms, the events in a simple wound where blood flow has occurredcan be described as following a reaction path where a) Blood cells leakinto a wound area; b) Blood vessels usually contract in the wound areato reduce the flow of blood; c) Platelets in the blood aggregate andadhere to tissue at the damaged site, even plugging small blood vessels;d) Platelets also interact with collagen, phospholipids, and tissuefactor (a lipid-containing protein or lipoprotein, that stimulates bloodclot formation); e) The platelets break-up and release thromboplastin, apoorly defined mixture of phospholipids and proteins that activate aseries or cascade of reactions, usually catalyzed by serine proteases.The final product of these reactions is the enzyme thrombin whichcatalysis the conversion of the soluble blood protein, fibrinogen, toinsoluble fibrin; f) The platelets provide nuclei upon which fibrin isbound to form the first stage of the moist clot, followed by subsequentmaturation of the clot to form a firm coherent mass; g) Tissue formingcells, fibroblasts, approach the wound and associate with the moist clotto strengthen the region; h) The clot contracts and dehydrates, usuallythrough evaporative processes, although there may be some absorption ofliquid into the tissue; i) Phagocytes (white blood cells) move into thewound area to ingest microorganisms, cellular debris and any residualforeign matter; j) Epidermal cells at the edge of the wound divide andbuild a bridge across the wound.

The actual chemical and biological processes involved in the clottingprocess are quite complex and sophisticated. The process must be veryselective, forming clots under only exacting conditions, so that clotformation does not occur in the circulatory system where clotting woulditself be dangerous, causing phlebitis and certain types of strokes.

Wound management and clotting enhancement for wounds has taken manydifferent paths over the years. There are a wide variety of differentmethodologies available for the management of wounds, depending, atleast in part upon the type of wound and its severity. The two mostcommon and effective treatments for minor bleeding wound management,following cleansing of the wound area, include direct application ofpressure to the wound area and the topical application of an absorptivebandage to the wound surface. To assure the reduction of direct orsecondary infections, all wound management should include cleansing andapplication of an antimicrobial agent to the wound area. After thiscleansing step, the other methods may follow to control bleeding andprevent contamination of the wound. Direct application of pressure isusually effected by application of pressure manually or with a lightwrapping. A sterile article is placed over the wound and pressureapplied to the wound through the sterile article (e.g., a fabric, suchas gauze, cotton ball, bandage, or other available, preferablysterilized or at least cleaned fabric). The pressure acts to assist inclosing blood vessels in the area to reduce blood flow, absorb some ofthe initial blood flow with the highest content of foreign mattercarried therein, and to stabilize the movement of the blood so thatclotting is given time to initiate. The application of bandages to thewound area primarily acts to absorb excess blood, flow, provide a longerterm barrier over the wound against introduction of foreign agents,protect the clot while it is still fragile (allowing it to dehydrate inthe first twenty-four hours), and possibly carry and retainantimicrobial material to the wound surface.

The use of lasers, alone or in combination with topically applied patchmaterials (e.g., an elastin patch made from animal tissue), has beensuggested for field treatment of bleeding wounds, both internal woundsand external or topical wounds. This has been specifically suggested asa field treatment, especially for the military, police, fire, and rescueservices. Lasers by themselves can cauterize and seal vessel and organwounds, and the patch can provide additional structural support for thearea. http://detnews.com/96/discover/9701/05/12300058.htm.

Many folk remedies have also been applied as abrasion, but not openwound, treatments. For example,www://.drchristopher.com/ail/abrasio3.htm suggests the use of specificnatural material treatments for abrasions where the skin has not beenbroken. The natural herbal agents include wheat grass chlorophyll,comfrey, healing ointment (comfrey, marshmallow, marigold, beeswax andoils), myrrh, plantain (and banana is also well known), and cayennepepper. These materials may be applied directly to the abrasion area orcarried on another surface, often with wetting suggested to retain theherbal abrasion treatment material. An Asian home remedy includes Dit DaJao (“Iron Wine) which is a tincture remedy applied to relieve pain,stimulate blood flow and chi flow, and break up clots and bruises. Thetincture is made up from powdered herbs and alcohol, with strainedherbal residue discarded and the liquid tincture applied to the woundsurface. The herbs to be used include Arnica blossom, comfrey, blessedthistle, goldenseal root, ginger root, Myrrh, sasparilla root, and witchhazel. Http://www.aikidofaq.com/n.sub.—section51.html)

Newer technology for wound management is the use of chemical bandages,or literally polymeric film-forming material over the wound area. Thistechnology has passed from a fairly unsophisticated application ofliquid glues (e.g., cyanoacrylate adhesives, gelatinous glues, and UVcurable polymers) to the wound surface. In 1998, only the second liquidglue was granted FDA approval for use as stitches in addition toclotting enhancement, the glue apparently comprising a formaldehydecontent cyanoacrylate. This glue is Closure Medical Corporation'sDermaBond™, which is used as an alternative to Baxter HealthCareCorporation's Tisseel™, which is made from two blood proteins thatnaturally cause blood to clot. The cyanoacrylate must have a strongtendency for tissue irritation and carries a standard recommendationagainst use with patients with sensitivities to acrylates andformaldehyde, which are fairly common. HealthCare Corporation'sTisseel™, which is made from specific blood proteins thrombin andfibrinogen, is relatively expensive to manufacture. In addition, the useof human or animal derived protein compositions carries the risk ofcontamination by infectious agents such as hepatitis viruses, HumanImmuno-Deficiency (HIV) viruses, or prions such as have been related tomad cow disease (bovine spongiform encephalitis) and Creutzfeld-Jakobdisease. The Cryoseal™ clotting system uses cryoprecititated proteinsobtained from the patients' blood as an adhesive. This fibrin glueadhesive is prepared and applied using a floor-standing, air-drivendevice in an operating theater.

U.S. Pat. No. 6,060,461 describes a method for enhancing the formationof clots on a wound of an animal where blood is present comprising thesteps of applying porous particles with dimensions of from about 0.5 to1000 micrometers to at least a portion of said wound where blood ispresent in said wound, allowing said porous particles to remain incontact with said blood in said wound while clotting initiates in saidwound. The porous particles may have molecular sieve cutoff valuesbetween about 5,000 Daltons and 200,000 Daltons. The pores may comprisefrom 5 to 75% by volume of the porous particles.

PCT Application Publication WO 00/27327 describes a novel hemostaticcomposition comprising a substance containing uncharged organic hydroxylgroups and a substance containing at least one of a halogen atom and anepoxy group, which composition induces rapid blood coagulation andhemostasis at a wound or bleeding site. Examples of methods ofapplication of the composition include, but are not limited to bags ofmaterials, patches and bandaid-type patches, segments to be packed intocavities, fibers, fabrics, and the like.

It is known that fibrin clots are formed in vivo based upon the reactionof fibrinogen and thrombin in the presence of calcium ions. The initialphase of wound healing starts after the formation of fibrin clot, andinvolves the mobilization of cells from surrounding undamaged tissue.Normally, the earliest cells mobilized to the wound are inflammatorywhere they are active for a period of at least 1-3 days followinginjury. Subsequently, they are displaced by cells of the mesenchymelineage which are immobilized into, navigate through and digest fibrinand replace fibrin with extracellular matrix (ECM) of different collagentypes, fibronectin and hyaloron. Endothelial cells also infiltrate thefibrin and generate microcapillary structures. Ultimately, these cellsreplace the provisional fibrin matrix with granulation tissue populatedby parenchymal cells and vasculature in secreted ECM.

Human fibroblasts are the major cellular entities responsible for theregeneration of the extracellular matrix (ECM) within the wound bed.Human fibroblasts also express specific membrane receptors to fibrinogenand thrombin. In the case of skin wounds, human fibroblasts reform thematrix of the dermis. For example, during the course of healing of anincisional skin wound, human fibroblasts are mobilized from thesurrounding tissue and enter into the fibrin clot, help dissolve it andgenerate as well as reform the collagens (i.e. type I and type III) inthe extracellular matrix. Based upon these properties of humanfibroblasts, fibroblast implants have been suggested as a means forsupplementing the body's natural wound healing regime (Gorodetsky, R.,et al. Radiat. Res. 125:181-186 (1991)).

Benzoylated hyaluronic acid (HA) sheets containing holes or pores havebeen used as a carrier for fibroblasts and keratinocytes for woundhealing (Andreassi, L., et al. Wounds 3(3): 116-126 (1991)).Specifically, HA sheets are cultured with these cells and then affixedto the site of the burn injury, where the cells migrate out of the sheetand accelerate the rate of wound regranulation. A major problem withimplanted HA sheets, however, is that they are not metabolized bytissue, are cumbersome to administer, and may result in long-termimmunological problems.

Purified fibrin(ogen) (which is known in the art as a mixture of fibrinand fibrinogen) and several of its lytic fragments (i.e. FPA, FPB, D andE) have been shown to be chemotactic to a variety of cells includingmacrophages, human fibroblasts (HF) and endothelial cells (Gorodetsky,R., et al. J. Lab. Clin. Med., in press (1997); Brown, L. F., et al.Amer. J. Pathol. 142:273-283 (1993); Clark, R. A. F., et al. J. Invest.Dermatol. 79:624-629 (1982); Ciano, P. S., et al. Lab. Invest. 54:62-69(1986); Dejana, E., et al. J. Clin. Invest. 75:11-18 (1985)). Thrombinalso has been shown to exert proliferative effect on various cellsincluding fibroblasts, endothelial cells, and to enhance wound healingin rat skin (Kang, Y. H., et al. J. Histochem. Cytochem. 39:413-423(1991); Shuman, F., NY Acad. Sci. 408:228-235 (1986); Biedermann, B., etal. J. Lab. Clin. Med. 124:339-347 (1994)).

Fibrin microbeads have been described in the prior art for use as drugdelivery systems ((Ho, et al. Drug Dev. and Ind. Pharm. 20(4):535-546(1994); Senderoff, et al. J. Parenteral Sci. & Tech. 45(1):2-6 (1991)).However, it has not been suggested or taught in the prior art that suchfibrin microbeads have chemotactic and/or proliferative effects on anycells. Furthermore, the fibrin microbeads of Ho, et al. and Senderoff,et al. would not be particularly useful or desirable as vehicles forculturing cells. In this regard, the Ho, et al. microbeads containglutaraldehyde which cross-links proteins and destroys certainbiologically active sites, thereby interfering with the binding of themicrobeads to cells. Glutaraldehyde treatment may also render themicrobeads immunogenic. The Senderoff, et al. microbeads containessentially the same relatively low degree of cross-linking as fibrin.Thus, the Senderoff, et al. microbeads are not stable in aqueoussolutions and therefore would not be useful as vehicles for culturingcells which require matrices that do not readily dissolve in aqueoussolutions. U.S. Pat. No. 6,150,505 describes novel fibrin microbeads andtheir method of manufacture, where the fibrin microbeads are provided inthe absence of glutaraldehyde.

One problem in the use of these medical or medicinal treatments is theapplication of the solids, particulates, fluid or otherwise flowablematerials to the desired site. Sprinkling a material over the surface ofa wound is effective, but can waste significant amounts of materials. Itis desirable to be able to apply the materials more uniformly andspecifically to a site. U.S. Pat. No. 6,241,697 shows a non-contactwound covering for covering a wound. A peripheral sealing ring iscovered by a barrier layer and this assembly is attached to the skinwith an adhesive. The barrier layer and peripheral sealing ring togetherdefine a treatment volume over the wound. The barrier layer may includeactive and passive heaters and the sealing ring may dispense water tocontrol the humidity of the treatment volume. One form of active heat isthe transfer of a heated fluid to the wound covering. In effect, anenclosed area is defined around a wound and liquid is directed into theenclosed area through a hose or tube.

U.S. Pat. No. 4,373,519 provides a system for removing liquids from awound to promote healing, and embeds absorbent materials into anon-woven web that is applied to a surface. The non-woven web may beadhesively secured to the wound area.

U.S. Pat. No. 6,992,233 (Drake) describes a hemostatic starch deliverysystem including a delivery system for the delivery of flowablemedicinal, therapeutic or medicine materials has a strip with flowablematerial contained and restrained therein. A removable seal is provided,so that when the removable seal is removed, the flowable material willflow from a storage area onto a site selected for treatment. Theremovable seal may be provided with additional features such asabsorbent coatings, or additional disinfectants coatings useful inpreparing the wound surface to receive the flowable wound treatmentmaterial. A preferred composition is a system, article and method forthe enhancement of clotting in wounds with extravascular blood flow,especially where the surface of the tissue has been broken.

Clot formation can be needed in many different environments andindividual structures and improved or optimized compositions can beneeded for each particular field of use.

SUMMARY OF THE INVENTION

A hemostatic surface application device having a region of hemostaticfoam for contact with a patient's skin where a wound exists or iscreated, the device includes: a release layer, the release layer incontact with a hemostatic flexible foam section, and a structural foamlayer having a front side and a back side surrounding the hemostaticflexible foam layer, forming a generally central hemostatic surfaceexposed through the front side of the surrounding structural foam layer,and a support layer adhered to the backside of the structural foamlayer.

A topical (and topically-applied), substantively non-transferringapplication of a medicinal or therapeutic device to surface tissue isused particularly for the reduction of bleeding, especially forenhancing the formation of clots on the surface of patients as wounddressing applied over vascular puncture sites and percutaneous cathetersites. The device includes a non-dissolvable hemostatic foam carried ona support. A strippable/removable cover protects the foam untilimmediately before application and before insertion of a puncture orcatheter through the applied device.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded side view of an embodiment of the therapeuticdevice of the invention.

FIG. 2 is a side view of an embodiment of the therapeutic device of thepresent invention applied to the skin of a patient and with a needlepenetrating through the device.

FIG. 2A is a vertical view of a device according to the scope of thepresent invention.

FIG. 2C is vertical view of a device according to the scope of thepresent invention, with an improved structure to facilitate direction ofwater through the device.

FIG. 3 is a non-limiting rendition of chemical structure for ahemostatic foam useful un the practice of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A hemostatic surface application device having a region of hemostaticfoam for contact with a patient's skin where a wound exists or iscreated, the device including: a release layer, the release layer incontact with a hemostatic flexible foam section, and a structural foamlayer having a front side and a back side surrounding the hemostaticflexible foam layer, forming a generally central hemostatic surfaceexposed through the front side of the surrounding structural foam layer,and a support layer adhered to the backside of the structural foamlayer.

A blood-flow reducing, hemostatic surface application device, whichresists or eliminates transfer of clotting material into a wound, isdescribed as having a region of hemostatic foam for contact with apatient's skin where a wound exists or is created. The device mayinclude a release layer. The release layer is in contact with ahemostatic flexible foam section, and a structural foam layer having afront side and a back side surrounding the hemostatic flexible foamlayer. The surrounding structure of the structural foam forms agenerally central hemostatic surface (of the hemostatic foam) exposedthrough the front side of the surrounding structural foam layer. It isdesirable that a support layer is adhered to the back side of thestructural foam layer. The hemostatic flexible foam layer should be ableto retain at least 99.5% of total weight of the hemostatic flexible foamlayer when in contact with a surface having a 5 micron thick layer ofwater on its surface for 1 minute. The hemostatic flexible foam layermay include a polysaccharide foam composition. The hemostatic flexiblefoam layer may include a polysaccharide foam composition. The device mayhave the hemostatic flexible foam layer with a thickness at least 1%greater than the thickness of the structural foam layer. The structuralfoam layer may a polyurethane foam, either closed cell, open-cell or thelike. Other foams may be used (as the foam has not chemical requirementsexcept to be non-irritating to skin, and performs only a structuraleffect), such as polysiloxane foams, polycellulosic foams, and otherpolymeric foams. The device may have the support layer adhered to thebackside of the structural foam layer by an adhesive layer.

A method of reducing excessive blood flow off an exterior surface woundof a patient comprising removing the release layer of the hemostaticsurface application device as described above, and applying thegenerally central hemostatic foam layer to a limited area of skin of thepatient. The method may be executed wherein, after applying thegenerally central hemostatic foam layer to a limited area of skin of thepatient, a catheter or needle is inserted through the hemostatic foamlayer of the hemostatic surface application device and into the skin ofthe patient. In this process, after inserting the catheter or needlethrough the skin of the patient, blood exudes from the skin of thepatient and is clotted by the hemostatic foam layer. Furthermore in thismethod, the hemostatic flexible foam layer retains at least 99.5% oftotal weight of the hemostatic flexible foam layer when in contact withblood exuding from the skin of the patient for 1 minute.

Hemostatic foam compositions are known in the medical field, but theyhave had limited numbers of variations in structural forms within thefield. Among known foams that can be used within the practice of thepresent invention are those shown by the following background art.

US Published Patent Application Document 2015/0314037 and 2014/0161738(Andreas) discloses a pharmaceutical hemostatic liquid foam basepreparation comprising albumin as foaming agent and a fibrinogenprecipitating substance and optionally a coagulation inducing agent,wherein albumin as foaming agent is present in native form; a method forthe production of a transient hemostatic liquid foam; the transienthemostatic liquid foam; and a kit for making the foam.

US Published Patent Application Documents 2017/0136054 and 2014/0010887and

2009/0062233 (Ji) evidences a modified starch material for biocompatiblehemostasis, biocompatible adhesion prevention, tissue healing promotion,absorbable surgical wound sealing and tissue bonding, when applied as abiocompatible modified starch to the tissue of animals. The modifiedstarch material, which may be in the form of a foam, produceshemostasis, reduces bleeding of the wound, extravasation of blood andtissue exudation, preserves the wound surface or the wound in relativewetness or dryness, inhibits the growth of bacteria and inflammatoryresponse, minimizes tissue inflammation, and relieves patient pain. Thehemostatic materials, which may be in foam form, can be provided byadding the functional group on the raw starch glucose units withchemical agents, e.g. by carboxylation modification, or hydroxylationmodification, the starch captures hydrophilic groups in its molecularstructure and obtains hydrophilic properties, By using bifunctional orpolyfunctional chemical agents to cross-link the raw starchmacromolecules or grafting external macromolecular hydrophilic groups tothe raw starch, the starch acquires enhanced hydrophilic properties andviscosity/adhesiveness in a water solution. The viscosity of modifiedstarch relates to the raw starch origin and the degree of substitutionof external and cross-linked or grafted functional groups, etc. Whencontacting blood, the hydrophilic and adhesive properties of themodified starch of the present invention produce a “starch-bloodcoagulation matrix” with strong adhesive characteristics which can sealwounded tissue and stop bleeding. In addition, the interaction betweenthe formed blood coagulation matrix and the functional groups of tissueproteins causes the “starch-blood coagulation matrix” to adhere to andseal the wounded tissue, resulting in hemostasis.

US Published Patent Application Document 2013/0096479 discloses ahemostatic product having a plurality of hemostatic layers. Each of thehemostatic layers includes a dextran support and at least one hemostaticagent, which is selected from the group consisting of thrombin andfibrinogen. The hemostatic layers are arranged in a stackedconfiguration. The thrombogenic agent may be applied onto open-cell orclosed-cell foam supports.

US Published Patent Application Document 20120114592 (Zuidema) isdirected to hemostatic foams and to the preparation of such foams. In afirst aspect, the present invention provides a biodegradable hemostaticfoam comprising a polymer blend of a water-soluble polymer and aphase-separated polyurethane comprising an amorphous segment and acrystalline segment, wherein at least said amorphous segment comprises ahydrophilic segment.

US Published Patent Application Document 2007/0172432 (Stopek) disclosesbiodegradable hemostatic compositions, including nucleic acids. Thenucleic acids may be obtained from plant sources, animal sources, orcombinations thereof, or they may be synthetic. The hemostaticcompositions are non-inflammatory, and are degraded in an animal's bodyafter successfully re-establishing hemostasis of a tissue site. Methodsfor utilizing such compositions are also provided.

All documents cited in this patent are incorporated herein by referencein their entireties.

Vascette™ VCD hemostatic applique' is a geometric (square, rectangular,oval, circular oo irregular shape), single use, multi-layer, topical,hydrophilic wound dressing applied over vascular puncture sites andpercutaneous catheter sites (before or after formation of the puncturewound). Vascette™ VCD is, by way of non-limiting example, a square (50mm×50 mm), multi-layer bandage that incorporates a topical hemostaticfoam agent. Foam dimensions are 25 mm×25 mm×4 mm (thick). The undersideof the bandage has a biocompatible adhesive coating with a protective,peel-away liner. The hemostatic foam is affixed to the center of thebandage and visible from the topside of the dressing. All materialsemployed in the device are biocompatible or low allergenic. Thestrippable cover layer need not be so limited. Upon application, therewill be no compression applied to the bandage. The hemostatic foam willbe positioned directly over the skin surface puncture site (section2.1.3 CAD drawings). The polysaccharide, ultra-hydrophilic foam rapidlyabsorbs water from blood, producing a hemoconcentration of solid bloodcomponents (platelets, red blood cells, fibrinogen, etc.), typicallyproducing hemostasis within four to six minutes after application.

2. Modified Starch Processing and Mode of Action: Starches are modifiedto enhance their performance in different applications. Starches may bemodified to increase their stability against excessive heat, acid,shear, time, cooling, or freezing; to change their texture; to decreaseor increase their viscosity; to lengthen or shorten gelatinization time;or to increase their visco-stability. Pursuant to FDA guidance,following is a description of the polysaccharide chemistry and modifiedstarch processing. AMP® particles or foam are plant derived modifiedstarch (chemical name: carboxyl starch sodium; CMS), which is a granularpolysaccharide polymer obtained by physical processes, includinggranulation and sieving. The particle size of AMP® is in the range of10˜300 μm. The sodium starch glycolate (CMS) contains no medicinalsubstance or human/animal derivatives. It is a cold water-soluble starchderivative having wide applications in the fields of pharmaceutical,textile, paper making, adhesive and absorbent. CMS is included in theUnited States Pharmacopoeia (USP NF36<5576>), Europe Pharmacopoeia (EP5.4 p. 4018-4019) and Chinese Pharmacopoeia (Ch.P. 2020 Vol 4 P791).Starch based hemostat particles have a broad range of applications andproven hemostatic effect. To date, there are no known product relatedadverse events. The foam configuration is preferably a lyophilizedversion of the AMP® particles contained in the Responder® topicalhemostat (K191377 pending). The foam tradename is SealFoam™ foamcushion. The CMS Foam Molecular Structure is similar to that shown inFIG. 3 .

The preferred polysaccharide components for the porous particles andporous beads of the present invention may often be made fromcross-linked polysaccharides, such as cross-linked dextran(poly[beta-1,6-anhydroglucose]) or starch(poly{alpha-1,4-anhydroglucose]). Dextran is a high molecular weightwater-soluble polysaccharide. It is not metabolized by humans, isnon-toxic, and is well tolerated by tissue in most animals, includingmost humans. There has even been extensive use of solubilized dextransas plasma substitutes. Similarly, beads prepared by cross linking starchwith epichlorohydrin are useful as hemostatic agents and are welltolerated by tissue. The starch particles are enzymatically degraded bytissue alpha-amylases and rapidly removed from the wound site. TheSephadexm™ beads specifically mentioned in the description ofparticularly useful polysaccharides comprise dextran crosslinked withepichlorihydrin. These beads arc available in a variety of bead sizes(e.g., 10 to 100 micrometers, with a range of pore size. It is believedthat pore sizes on the order of from 5 to 75% of volume may becommercially available and can be expanded to from 5 to 85% by volume ormanufactured with those properties from amongst the type of beadsdescribed above. The sizes of the pores may also be controlled to act asmolecular sieves, the pore size being from 0.5% or 1 to 15% of thelargest diameter of the particles or beads. The Sephadex™ beads arepromoted as having controlled pore sizes for molecular weight cutoff ofmolecules during use as a sieve, e.g., with cutoff molecular beingprovided at different intervals between about 5,000 Daltons and 200,000Daltons. For example, there are cutoff values specifically for molecularweight sizes of greater than 75,000 Daltons. This implies a particlesize of specifically about 10 to 40 microns. These beads will rapidlyabsorb water, swelling to several times their original diameter andvolume (e.g., from 5 to as much as twenty times their volume). Similartechnology can be used to produce cross linked starch beads withproperties similar to the Sephadex™ particles. Other solublepolysaccharides such as sodium alginate or chitosan can be used toprepare cross linked beads with controlled porosity and size.

Major classes of pressure-sensitive adhesives include tackified naturalrubbers; synthetic rubbers such as butyl rubber; and tackified linear,radial, star, and branched and tapered styrene block copolymers, such asstyrene-butadiene, styrene-ethylene/butylene and styrene-isoprene;polyurethanes; polyvinyl ethers; acrylics, especially those having longchain alkyl groups; poly-.alpha.-olefins; and silicones.

Generally, when additives are used to alter properties ofpressure-sensitive adhesives, the additives need to be miscible with thepressure-sensitive adhesive or to form homogeneous blends at themolecular level. Some types of pressure-sensitive adhesives have beenmodified with tackified thermoplastic elastomers, thermoplastics, andelastomers. For example, thermoplastic materials have been added topolymerized hot melt acrylic pressure-sensitive adhesives wherein thethermoplastic is a packaging material or recyclable tape backings. Inthese cases, the type and amount of thermoplastic material is controlledso that the thermoplastic material can function as a packaging materialwhile avoiding degradation of the adhesive properties of thepressure-sensitive adhesive.

However, more often than not when a non-tacky thermoplastic additive isblended with a pressure-sensitive adhesive, reduction of the overalladhesive properties of the blend (as compared to the pressure-sensitiveadhesive only) are observed. Thermoplastic polymers have been added tostyrene block copolymer adhesives to reduce the tack of the resultingpressure-sensitive adhesives for application of protective sheets tolarge area surfaces.

Pressure-sensitive adhesives, whether modified or not have been used formore than half a century for a variety of purposes. Generally,pressure-sensitive adhesives are used in tapes wherein a tape comprisesa backing, or substrate, and a pressure-sensitive adhesive. Typically, apressure-sensitive adhesive adheres with no more than applied fingerpressure and can be permanently tacky.

In the medical field, pressure-sensitive adhesive tapes are used formany different applications in the hospital and health areas. For mostapplications, tapes are applied directly to a patient's skin. It isimportant that the pressure-sensitive adhesive tape be compliant andnon-irritating to the skin, as well as adhering to the skin withoutcausing damage to the skin when the tape or adhesive coated article isremoved. A particularly useful medical application forpressure-sensitive adhesive tapes and articles is in the field oftransdermal patches. Such patches can be used as drug transportmembranes or to attach drug transport membranes to skin.

Although pressure-sensitive adhesive tapes and articles are widely usedin the medical field, pressure-sensitive adhesive tapes and articlesfind widespread use in many other applications. For example, transfertapes can be used to adhere two surfaces together such as the flaps ofpacking material or fabric to a surface. However, transfer tapeadhesives generally have little tensile strength and one solution hasbeen to add glass fibers to provide tensile strength.

Pressure-sensitive adhesives require a delicate balance of viscous andelastic properties that result in a four-fold balance of adhesion,cohesion, stretchiness and elasticity. Pressure-sensitive adhesivesgenerally comprise elastomers that are either inherently tacky, orelastomers or thermoplastic elastomers that are tackified with theaddition of tackifying resins.

FIG. 1 is an exploded side view of an embodiment of the therapeuticdevice 100 of the invention. Shown in the device 100 is a release layer102 and an optional adhesive layer 104 (which will not bloc access tothe hemostatic foam layer 108. Surrounding the hemostatic foam layer 108is the structural foam layer 104. An adhesive layer 110 secures thehemostatic layer 108 and the structural foam layer 104 to a supportlayer 112. The release layer 102 is removed and the structural foamlayer 104 and the hemostatic foam layer 108 are pressed against the area(e/g/. skin, not shown) to be addressed by treatment with the device100.

FIG. 2 is a side view of an embodiment of the therapeutic device 200 ofthe present invention (after removal of the strippable release layer 102of FIG. 1 ) applied to the skin of a patient 202 and with a needle 218penetrating through the device 200. The hemostatic foam layer 206 andthe structural foam layer 204 are pressed against the skin 202 of thepatient. The adhesive layer 208 212 is shown as more of a structurallayer, putting tension on the edges 214 of the hemostatic foam layer 206to assure firm contact of the hemostatic layer 206 against the skin 202.The support layer 210 is now distal from the skin 202. A needle orcatheter 218 is shown penetrating through the support layer 210 at apoint 220. The needle or catheter 218 continues passing through theadhesive layer 208 and through the hemostatic foam layer 206 and intothe skin 202 of the patient. The interface 216 between the hemostaticfoam layer 206 and the skin 202 to create a hemostatically active line216 where blood from the needle or catheter 218 penetrating the skinwill clot.

FIG. 2A is a vertical view of a device 250 according to the scope of thepresent invention. The support layer 252 is behind the structuralsupport foam 258 and the hemostatic foam layer 260. The strippablerelease layer 254 is shown over both the structural foam layer 258 andthe hemostatic foam layer 260. A notch 256 is shown to facilitateremoval of the release layer 254.

FIG. 2C shows the vertical view of the device 250 of FIG. 2A used as adressing with an improvement in the addition of an opening 264 thatprovides a window in the hemostatic foam layer 260. Beneath the windowlies a foam layer 258 acting as a pad which is preferably thehemostatic, polysaccharide starch described herein in the practice ofthe invention. When the hemostatic starch is applied to a bleedingarteriotomy it rapidly absorbs water, creating a gelatinous mass whichhas a robust hemostatic reaction and is vigorously adhesive. Whenremoval of the dressing is required, it is necessary to irrigate watervia the large window directly above the adhesive hemostat. Generousirrigation neutralizes adhesivity, facilitating removal of the dressingwithout disturbing the clotted arteriotomy.

If a wrap or cover is present over the applied dressing, it is of courseremoved before water is applied through the hole 264. The surface areaof the hole 264 should be sufficient to allow situationally desirablerapid access for the water to the adhesive starch, typically within 1-45seconds in sufficient amount to enable release of the dressing byreducing the degree of adhesiveness of the adhesive starch. The size ofthe hole 264 with respect to the hemostatic foam layer 260. The surfacearea of the hole 264 with respect to the surface area of the hemostaticfoam layer 260 should be between 15% and 85% in square centimeters andpreferably between 25% and 75%. The relative dimensions are a balancebetween the need for enabling speed of release and protecting thehemostatic foam layer 260 from early release from ambient moisture. Thehole 264 also allows any excess moisture to be wiped off the top of thedressing.

All numbers in FIG. 2C that are common to FIG. 2A are identical elementsas between the two Figures.

FIG. 3 is a non-limiting rendition of chemical structure for ahemostatic foam useful un the practice of the present invention.

Other variations in the compositions and dimensions and structure of thedevice can be practiced without deviating from the scope of theinvention set forth in the claims.

These and other aspects of the invention will be further understood byreference to the figures.

What is claimed:
 1. A hemostatic surface application device having a region of hemostatic foam for contact with a patient's skin where a wound exists or is created, the device comprising: a release layer, the release layer in contact with a hemostatic flexible foam section, and a structural foam layer having a front side and a back side surrounding the hemostatic flexible foam layer, forming a generally central hemostatic surface exposed through the front side of the surrounding structural foam layer, and a support layer adhered to the back side of the structural foam layer.
 2. The device of claim 1 wherein the hemostatic flexible foam layer retains at least 99.5% of total weight of the hemostatic flexible foam layer when in contact with a surface having a 5 micron thick layer of water on its surface for 1 minute.
 3. The device of claim 1 wherein the hemostatic flexible foam layer comprises a polysaccharide foam composition.
 4. The device of claim 3 wherein the hemostatic flexible foam layer comprises a polysaccharide foam composition.
 5. The device of claim 2 wherein the hemostatic flexible foam layer comprises a polysaccharide foam composition.
 6. The device of claim 1 wherein the hemostatic flexible foam layer has a thickness at least 1% greater than the thickness of the structural foam layer.
 7. The device of claim 1 wherein the structural foam layer is a polyurethane foam.
 8. The device of claim 5 wherein the structural foam layer is a polyurethane foam.
 9. The device of claim 8 wherein the support layer is adhered to the backside of the structural foam layer by an adhesive layer.
 10. A method of reducing excessive blood flow off an exterior surface wound of a patient comprising removing the release layer of the hemostatic surface application device of claim 1 and applying the generally central hemostatic foam layer to a limited area of skin of the patient.
 11. The method of claim 10 wherein after applying the generally central hemostatic foam layer to a limited area of skin of the patient, a catheter or needle is inserted through the hemostatic foam layer of the hemostatic surface application device and into the skin of the patient.
 12. The method of claim 11 wherein after inserting the catheter or needle through the skin of the patient, blood exudes from the skin of the patient and is clotted by the hemostatic foam layer.
 13. The method of claim 12 wherein the hemostatic flexible foam layer retains at least 99.5% of total weight of the hemostatic flexible foam layer when in contact with blood exuding from the skin of the patient for 1 minute.
 14. The method of claim 13 wherein the hemostatic flexible foam layer comprises a polysaccharide foam composition.
 15. The method of claim 14 wherein the hemostatic flexible foam layer has a thickness at least 1% greater than the thickness of the structural foam layer.
 16. The method of claim 14 wherein the structural foam layer is a polyurethane foam.
 17. The hemostatic surface application device of claim 3 wherein the structural foam layer has a hole through it allowing direct moisture contact to the hemostatic flexible foam layer.
 18. The hemostatic surface application device of claim 1 wherein the structural foam layer has a hole through it allowing direct moisture contact to the hemostatic flexible foam layer.
 19. The method of claim 10 wherein the structural foam layer has a hole through it allowing direct moisture contact to the hemostatic flexible foam layer and moisture is applied through the hole, reducing the adhesiveness of the hemostatic flexible foam layer prior to removing the hemostatic surface application device from the skin of the patient.
 20. The method of claim 13 wherein the structural foam layer has a hole through it allowing direct moisture contact to the hemostatic flexible foam layer and moisture is applied through the hole, reducing the adhesiveness of the hemostatic flexible foam layer prior to removing the hemostatic surface application device from the skin of the patient 